School IPM Best Practices

Carpenter Ant, Camponotus pennsylvanicus

Carpenter ant

Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org.

IPM Steps to Reduce Carpenter Ants

1. Sample for Pest

Before taking any action, confirm the presence of more than one ant—it may have come in on clothing or packaging. Inspect the adjacent areas along walls (interior and exterior) now and again later. An ant or two may be searching for a food source—don’t let them find it! Develop a knowledge of where ants are likely entering and make a practice to inspect and anticipate.

Where to find it while inspecting: Create a “map” of the area and mark possible nest sites or entrances. Use flashlights, knee pads and small containers for collection. A small mirror to expand your visual expansion is helpful. Carpenter ants prefer to feed at night, but actively move between food source and the colony around the clock. Look for small piles of sawdust around moisture-damaged wood. This wood is easier to excavate and the moisture helps larvae survive. Search for nests in wall voids—any “hollow” area in wood is an appealing site for the queen to start a colony. Look for “satellite” nests nearby. You may find “colony debris” (insect parts, pupal casings) along with the sawdust. A popular site for nests is an entryway through a damp, wooden window or door sill. Always look for live ants in shady or dark places. They will almost always be following a trail. Indoors, the pheromone trail may follow electrical lines and water pipes.

2. Proper ID

To best treat a pest, you must be sure what it is.

Size and Particulars: Generally black, 1/4 to 1/2" (3.5–13 mm), has a small “waist” (termites do not have a thin waist between thorax and abdomen), (if winged, ants have smaller back wing than the front wing while termite wings are equal size), antennae are bent.

3. Learn the Pest Biology

Ants follow scent trails to and from food sources. Carpenter ants choose moist wood for nesting sites.

Life Cycle: Ants live in social nests. After fertilization, a queen begins a colony by caring for her eggs, then the hatching larvae and pupal stages. Those first new ants are her workers and care for the next young. A mature colony will send out new queens and males to start new colonies—this is the time you see flying ants.

Preferred Food Sources: Contrary to common opinion, carpenter ants do not eat wood. They eat insects and honeydew (aphid excrement) and most foods they find in your building. Due to this preference, ant baits should contain both protein grease and something sweet to increase their attraction.

Preferred Habitat: Carpenter ants prefer to live inside hollow, decaying wood such as under wood piles, in tree stumps or wooden framed buildings. Any wet wood near or under a home makes a suitable colony site and they will forage as far as 300 feet from the nest.

4. Determine Threshold

If you’ve seen carpenter ant activity, you need to act.

Threshold: If you’ve seen one or two carpenter ants, you need to act.

5. Choose Tactics

IPM for indoor pests is always a combination of exclusion and sanitation: Don’t provide access to water, food and shelter!

Best Management Practices: The number one way to reduce or prevent any ant pest in your building is to keep all food sources in closed containers, and keep all surfaces clean. Reduce moisture—fix leaks, insulate sweating pipes, promote ventilation. Clean gutters and keep downspouts working well. Replace all water-damaged wood. Keep floors swept and mopped, drain away standing water and remove food debris often. Give all food areas a good cleaning for grease and debris. (This includes drains, vents, cooking equipment, carts and the hard-to-reach areas behind and under counters, walls, and shelving.) Use soapy water to wash anything that may have food residue. Remove all garbage promptly (use plastic bag liners in cans as well). Carpenter ants prefer to nest in decaying wood. Check for their presence in framing and timbers that are part of the building or landscape.

Treatment Methods: Locate the nest, remove it by vacuuming with an industrial vacuum (vacuum up some corn starch as well), and then destroy the vacuumed material. This will reduce but will probably not destroy all ants as a nest will contain a few dozen to a few thousand ants, and not all will be in the nest at the time. Low-toxicity methods (do not use if you are also using a bait)—place near the nest: diatomaceous earth, a desiccant which dries out the insect bodies; pyrethrum products, a chrysanthemum derivative; silica, another desiccant sometimes sold in combination with pyrethrum; commercial products containing boric acid, an effective poison for insects with low toxicity to humans, but must be used with extreme caution and may not be suitable or legal in your district. ALWAYS READ THE LABEL FOR ANY PRODUCT'S SPECIFIC DIRECTIONS.

Insecticide Options: Bait traps contain insecticide introduced in a food source. Due to the nature of the bait trap and the amount of insecticide, they are generally considered safe for use in schools and homes. Keep out of reach of children. For a bait to be effective you must: 1) reduce any other access to a food source—sanitation and exclusion by keeping all foods in airtight containers. 2) do not kill ants as they must carry the food (bait) back to the colony where it will be a deadly food source for the colony. You may see an increase in ants at first but then a slow decline. Do not spray insecticides at this time. Be patient. Some instances of infestation may prompt a pesticide applicator to do a perimeter treatment, but it may be less than 100% effective if habitat is not changed.

6. Evaluate

Was the tactic successful? Record the date pests were first noted, and the tactic you used, and its success. Use one of our RECORD KEEPING tools.

For More Information:

University of Connecticut IPM for Carpenter Ants

University of Massachusetts IPM Practices for Carpenter Ants

Managing Ants Safely In and Around Schools (PDF)

CCE Suffolk County Horticulture Diagnostic Laboratory: Carpenter Ants (PDF)

Carpenter Ants Renovating Your Home? Use IPM to Give Them Their Marching Papers (PDF)


When a pesticide application is necessary, all necessary and required precautions are taken to minimize risk to people and the environment and to minimize risk of pesticide resistance or pest resurgence. Pesticide use in your school may be prohibited or regulated by local policies or state and federal regulations. Risk reduction methods can include, but are not limited to, spot-treatment, the use of gel or paste bait formulations placed in inaccessible locations, injection into a crack or crevice, and other methods that reduce potential exposure.